The present invention relates generally to gas pressure driven liquid pumps. More particularly, the present invention relates to an improved gas pressure driven liquid pump utilizing redundant pump mechanisms.
Condensate removal systems in steam distribution arrangements often utilize a motive gas driven pump that functions without electricity. Typically, such pumps include a tank (i.e., pump body) with a liquid inlet and a liquid outlet. The inlet and outlet, located near the bottom of the tank, are equipped with an inlet check valve and an outlet check valve to permit liquid flow in only a pumping direction. A pair of interconnected valves are controlled by a pump mechanism to open and close a gas motive port and a gas exhaust port as desired.
The pump operates by alternating between a liquid filling phase and a liquid discharge phase. During the liquid filling phase, the gas motive port is closed while the gas exhaust port is open. A float connected to a snap acting linkage rises with the level of liquid entering the tank. When the float reaches a high level position, the linkage snaps over to simultaneously open the motive port and close the exhaust port. As a result, motive gas enters the tank and the pump switches to the liquid discharge phase.
In the liquid discharge phase, steam or other motive gas is introduced into the pump tank through the motive port. The motive gas forces liquid out of the tank, causing the float to lower with the level of the liquid. When the float reaches a low level position, the linkage snaps over to simultaneously open the exhaust port and close the motive port. As a result, the pump will again be in the liquid filling phase.
Examples of prior art devices can be found in U.S. Pat. No. 5,938,409 to Radle and U.S. Patent Application Pub. No. 2004/0151597 to Dukes et al., both of which are herein incorporated fully by reference.